/*
 * Copyright 2020 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.tsunami.plugins.detectors.credentials.ncrack;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Multimap;
import com.google.common.flogger.GoogleLogger;
import com.google.tsunami.common.command.CommandExecutionThreadPool;
import com.google.tsunami.common.data.NetworkServiceUtils;
import com.google.tsunami.plugins.detectors.credentials.ncrack.client.NcrackClient;
import com.google.tsunami.plugins.detectors.credentials.ncrack.client.NcrackClient.TargetService;
import com.google.tsunami.plugins.detectors.credentials.ncrack.client.NcrackClient.TimingTemplate;
import com.google.tsunami.plugins.detectors.credentials.ncrack.client.data.NcrackRun;
import com.google.tsunami.plugins.detectors.credentials.ncrack.provider.TestCredential;
import com.google.tsunami.plugins.detectors.credentials.ncrack.tester.CredentialTester;
import com.google.tsunami.proto.NetworkService;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import javax.inject.Inject;
import javax.inject.Provider;

/**
 * Credential tester using the ncrack brute forcer. See {@link NcrackCredentialTester#SERVICE_MAP}
 * for list of supported services.
 */
final class NcrackCredentialTester extends CredentialTester {
  private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();

  private static final ImmutableMap<String, TargetService> SERVICE_MAP =
      ImmutableMap.<String, TargetService>builder()
          // Missing from TargetService: JOOMLA, HTTP, OWA
          .put("ssh", TargetService.SSH)
          .put("rdp", TargetService.RDP)
          .put("ftp", TargetService.FTP)
          .put("wordpress", TargetService.WORDPRESS)
          .put("telnet", TargetService.TELNET)
          .put("pop3", TargetService.POP3)
          .put("imap", TargetService.IMAP)
          .put("cvs", TargetService.CVS)
          .put("smb", TargetService.SMB)
          .put("smb2", TargetService.SMB2)
          .put("vnc", TargetService.VNC)
          .put("sip", TargetService.SIP)
          .put("redis", TargetService.REDIS)
          .put("postgressql", TargetService.PSQL)
          .put("mysql", TargetService.MYSQL)
          .put("mssql", TargetService.MSSQL)
          .put("mqtt", TargetService.MQTT)
          .put("mongodb", TargetService.MONGODB)
          .put("cassandra", TargetService.CASSANDRA)
          .put("winrm", TargetService.WINRM)
          .put("dicom", TargetService.DICOM)
          .build();

  private final Provider<NcrackClient> ncrackClientProvider;
  private final Executor executor;

  @Inject
  NcrackCredentialTester(
      Provider<NcrackClient> ncrackClientProvider, @CommandExecutionThreadPool Executor executor) {
    this.ncrackClientProvider = checkNotNull(ncrackClientProvider);
    this.executor = checkNotNull(executor);
  }

  @Override
  public String name() {
    return "NcrackCredentialTester";
  }

  @Override
  public String description() {
    return String.format(
        "Ncrack credential tester supporting the following services: %s",
        String.join(", ", SERVICE_MAP.keySet()));
  }

  @Override
  public boolean canAccept(NetworkService networkService) {
    return SERVICE_MAP.containsKey(NetworkServiceUtils.getServiceName(networkService));
  }

  @Override
  public ImmutableList<TestCredential> testValidCredentials(
      NetworkService networkService, List<TestCredential> credentials) {
    if (!canAccept(networkService)) {
      return ImmutableList.of();
      // TODO(b/145315535): reenable this once Tsunami has plugin matching functionality.
      // throw new UnsupportedTargetOrServiceException(
      //     String.format("Service %s is not supported", service.serviceName()));
    }

    try {
      // We use a Provider here to get a new NcrackClient object because this function might be
      // called multiple times in the client code.
      NcrackRun result =
          ncrackClientProvider
              .get()
              .withTimingTemplate(TimingTemplate.NORMAL)
              .withQuitCrackingAfterOneFound()
              .withNetworkEndpoint(networkService.getNetworkEndpoint())
              .usingUsernamePasswordPair(
                  generateTestCredentialsMapFromListOfCredentials(credentials))
              .onTargetService(getTargetService(networkService))
              .run(this.executor);

      return result.discoveredCredentials().stream()
          .filter(discoveredCredential -> discoveredCredential.username().isPresent())
          .map(
              discoveredCredential ->
                  TestCredential.create(
                      discoveredCredential.username().get(), discoveredCredential.password()))
          .collect(ImmutableList.toImmutableList());
    } catch (IOException | InterruptedException | ExecutionException e) {
      logger.atSevere().withCause(e).log("Error executing ncrack.");
      return ImmutableList.of();
    }
  }

  private static TargetService getTargetService(NetworkService networkService) {
    return SERVICE_MAP.get(NetworkServiceUtils.getServiceName(networkService));
  }

  private static Multimap<String, String> generateTestCredentialsMapFromListOfCredentials(
      List<TestCredential> credentials) {
    Multimap<String, String> map = ArrayListMultimap.create();
    credentials.forEach(c -> map.put(c.username(), c.password().orElse("")));
    return map;
  }
}
